import pymysql
from DBUtils.PooledDB import PooledDB


class SQLHandler(object):
    def __init__(self, host, port, db_username, db_password, db_name):
        # pip install --default-timeout=100 dbutils
        self.pool = PooledDB(
            # 使用链接数据库的模块import pymysql
            creator=pymysql,
            # 连接池允许的最大连接数，0和None表示不限制连接数
            maxconnections=6,
            # 初始化时，链接池中至少创建的空闲的链接，0表示不创建
            mincached=2,
            # 链接池中最多闲置的链接，0和None不限制
            maxcached=5,
            # 链接池中最多共享的链接数量，0和None表示全部共享。
            # 因为pymysql和MySQLdb等模块的 threadsafety都为1，
            # 所有值无论设置为多少，maxcached永远为0，所以永远是所有链接都共享。
            maxshared=3,
            # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错
            blocking=True,
            # 一个链接最多被重复使用的次数，None表示无限制
            maxusage=None,
            # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]
            setsession=[],
            # ping MySQL服务端，检查是否服务可用。
            #  如：0 = None = never, 1 = default = whenever it is requested,
            # 2 = when a cursor is created, 4 = when a query is executed, 7 = always
            ping=0,

            # 数据库信息
            host=host,
            port=int(port),
            user=db_username,
            password=db_password,
            database=db_name,
            charset='utf8'
        )

    def create_conn_cursor(self):
        # 创建连接
        conn = self.pool.connection()
        # 创建游标
        cursor = conn.cursor(pymysql.cursors.DictCursor)
        # 返回conn, cursor
        return conn, cursor

    def fetch_one(self, sql, args):
        try:
            conn, cursor = self.create_conn_cursor()
            cursor.execute(sql, args)
            result = cursor.fetchone()
            cursor.close()
            conn.close()
        except Exception as e:
            print('数据查询出现异常' + str(e))
            with open("../logs/db_select_many.log", "a+") as f:
                f.write(str(e) + "\n")
                result = None
                cursor.close()
                conn.close()
        return result

    def fetch_many(self, sql, args):
        conn, cursor = self.create_conn_cursor()
        try:
            cursor.execute(sql)
            result = cursor.fetchmany(args)
            cursor.close()
            conn.close()
        except Exception as e:
            print('数据查询出现异常' + str(e))
            with open("../logs/db_select_many.log", "a+") as f:
                f.write(str(e) + "\n")
                result = None
                cursor.close()
                conn.close()
        return result

    def fetch_all(self, sql, args=None):
        conn, cursor = self.create_conn_cursor()
        try:
            cursor.execute(sql, args)
            result = cursor.fetchall()
            cursor.close()
            conn.close()
        except Exception as e:
            print('数据查询出现异常' + str(e))
            with open("../logs/db_select_all.log", "a+") as f:
                f.write(str(e) + "\n")
                result = None
                cursor.close()
                conn.close()
        return result

    def insert_one(self, sql, args):
        conn, cursor = self.create_conn_cursor()
        try:
            res = cursor.execute(sql, args)
            conn.commit()
            # print(res)
            conn.close()
        except Exception as e:
            print('数据插入出现异常' + str(e))
            with open("../logs/db_insert.log", "a+") as f:
                f.write(str(e) + "\n")
            conn.rollback()
            conn.close()
        return res

    def insert_many(self, sql, args):
        conn, cursor = self.create_conn_cursor()
        try:
            res = cursor.executemany(sql, args)
            conn.commit()
            conn.close()
        except Exception as e:
            print('数据插入出现异常' + str(e))
            with open("../logs/db_insert.log", "a+") as f:
                f.write(str(e) + '\n')
            conn.rollback()
            conn.close()
        return res

    def update(self, sql, args):
        conn, cursor = self.create_conn_cursor()
        res = cursor.execute(sql, args)
        conn.commit()
        # print(res)
        conn.close()
        return res

    def delete(self, sql, args):
        conn, cursor = self.create_conn_cursor()
        res = cursor.execute(sql, args)
        conn.commit()
        # print(res)
        conn.close()
        return res


# 测试样例
try:
    sqlhelper = SQLHandler("127.0.0.1", 3306, "root", "123456", "zhihu")
    print("connection success")
    sql = "SELECT answer_id FROM `basic_zhihu_answer` where comment_id = %s "
    res = sqlhelper.fetch_one(sql,"19557991856")
    print(res)
except Exception as e:
    print(e)
    with open("wrong.txt", "a+") as f:
        f.write(str(e) + '\n')
